RF64 with 4GB+ size is mistaken as WAV

I’ve used Audacity for a long time now, mainly for the generation of extreme-lengthed audios (in MP3 or OGG). I once tried to render a long file (all in signed 16-bit PCM) in WAV, but wasn’t able to export it, which was because WAV used 32-bit file sizes. I recently recreated that project in Audacity (finding out that RF64 or RIFF 64 is WAV but with 64-bit file sizes), and hitting Export on RF64 (as signed 16-bit PCM) tells me the same message for 4GB+ WAVs:
“You have attempted to Export a WAV or AIFF file which would be greater than 4GB. Audacity cannot do this, the Export was abandoned.” And again, this is in RF64. I even tried W64 (SoundFoundry WAVE 64) and RAW, but it gives me the same message. Is anyone able to help me on this, or is this just a bug?

Using Audacity 2.3.2 on Windows 10 build 18362, FFmpeg: F(55.33.100), C(55.52.102), U(52.66.100)

Is anyone able to help me on this, or is this just a bug?

Neither one. This is the longer WAV extension. Normal WAV files cut you off at 2GB. Special extended ones will get you out to 4GB. If you open a longer one in a very old player, it may fail. I have sound recorders which will insist on 2GB uncompressed sound files, not 4.

I think you can do what you want in FLAC. It’s lossless, gently compressed and I’m not sure what the size limit is.

You need to be super careful about your goals. Not everybody can open FLAC files. and you can’t make WAV that do what you want. MP3s will do that, but MP3 always creates progressive compression distortion and you can’t stop it.

I’m not sure what the size limit is.

Apparently, there’s a lot of discussion about this. Write back when you find out.


That’s not correct. “Normal” WAV files cut you off at 4GB.
This is because a normal WAV file uses 32-bit addressing and at 4GB the file runs out of unique addresses for the samples. Some systems (usually antiques) may not be able to handle WAV files over 2 GB due to other limitations, but that is not an inherent limitation of the file format.
There’s some additional info in the manual: Export Formats supported by Audacity - Audacity Manual

Assuming that you are doing that by using “Export Audio” and selecting “other compressed files” and then selecting “RF64” as the “header”, then that’s a bug. It has been fixed in the development code, so it will be fixed in the next release of Audacity.

The problem was that previously there was no warning when exporting oversized files, and would just create a file that would not play. That was fixed by adding the warning, but I think that the person fixing it forgot that some “WAV” files (namely “RF64 WAV”) don’t suffer from the 4GB limit.

I’d suggest that you export in FLAC format, then if necessary, use a 3rd part converter to change the format to “RF64 WAV” (I think foobar2000 can do that).
Alternatively, split the track into smaller sections so that the files are less than 4GB each (you could use “labels” and “Export Multiple” for splitting)

Well, uhh thanks! I did do “uncompressed files” and then that RF64 or whatever. I actually tried encoding it in Matroska (.mka) in signed 16-bit PCM with FFmpeg, and it completely worked.